JP4089831B2 - Multi-vortex flow meter with integrated pressure gauge - Google Patents

Description

  The present invention relates to a multi-vortex flow meter having both the function of a vortex flow meter and the function of a thermal flow meter, and more particularly to a multi-vortex flow meter in which a pressure gauge is integrated.

  In order to measure the flow rate of the fluid to be measured flowing in the flow tube, a vortex flow meter or a thermal flow meter is used.

  As is well known, when a vortex generator is arranged in a fluid flow, the vortex flowmeter is the number of Karman vortices (vortex frequency) generated from the vortex generator within a unit time within a predetermined Reynolds number range. Is proportional to the flow rate regardless of gas or liquid. This proportionality constant is called the Strouhal number. Examples of the vortex detector include a thermal sensor, a strain sensor, an optical sensor, a pressure sensor, an ultrasonic sensor, and the like, which can detect a thermal change, a lift change, and the like due to the vortex. The vortex flowmeter is a simple flowmeter that can measure the flow rate without being affected by the physical properties of the fluid to be measured, and is widely used for measuring the flow rate of gas or fluid (see, for example, Patent Document 1).

  The thermal flow meter includes a temperature sensor (fluid temperature sensor) and a heating temperature sensor (heating temperature sensor), and is a heating temperature sensor (flow velocity) having the functions of a temperature sensor and a heating sensor. The temperature of the sensor (heater) is controlled to be a constant temperature difference with respect to the temperature measured by the temperature sensor. This is because the amount of heat taken away from the heater when the fluid to be measured flows is correlated with the mass flow rate, and the mass flow rate is calculated from the amount of heating power to the heater (see, for example, Patent Document 2). ).

  Patent Document 3 listed below discloses a technique for a multi-vortex flow meter that has both the function of a vortex flow meter and the function of a thermal flow meter. The multi-vortex flow meter can accurately measure from a minute flow rate to a large flow rate, and this point is particularly superior to other flow meters.

  In the multi-vortex flow meter, the function of the vortex flow meter and the function of the thermal flow meter are selectively used according to the flow state of the fluid to be measured flowing through the flow path of the flow tube. That is, measurement is performed by the function of the thermal flow meter in the minute flow rate region and the low flow rate region, and measurement is performed by the function of the vortex flow meter in the high flow rate region.

In vortex flowmeters, the sensitivity of the vortex detector becomes insufficient when the flow rate decreases and the vortex differential pressure decreases, so the multi-vortex flowmeter switches the function to the thermal flowmeter at a predetermined lower limit flow rate. Control is being made.
Japanese Patent No. 2869054 (Page 3, Fig. 1) JP 2004-12220 A (Page 6, FIG. 4) JP 2006-29966 A (page 4-8, FIG. 1-5)

  The inventor of the present application has found that, even if the flow rate is low, the vortex differential pressure increases as the pressure in the flow tube increases, and this makes it possible to lower the lower limit flow rate that is a criterion for switching the function of the flow meter. I would like to reflect this finding in the multi-vortex flowmeter. The inventor of the present application wants to measure the flow rate using the function of the vortex flowmeter as much as possible in order to take advantage of the vortex flowmeter. For this reason, this inventor thinks that it is necessary for a multi vortex flowmeter to provide the pressure gauge which grasps | ascertains the pressure fluctuation in a flow tube.

  This invention is made | formed in view of the situation mentioned above, and makes it a subject to provide the pressure gauge integrated multi vortex flow meter used as a better multi vortex flow meter.

The multi-vortex flow meter integrated with a pressure gauge according to claim 1 of the present invention, which has been made to solve the above-mentioned problems, is provided in a flow path, is formed in a cylindrical shape having a square tube cross section, and is measured A measuring tube that is formed to extend along a direction in which the fluid flows, and that allows the fluid to be measured to pass therethrough, and a portion in which the fluid to be measured flows in the measuring tube so as to face the flow of the fluid to be measured, A vortex generator provided so as to be located in the center of the opening portion of the measurement tube on the side into which the fluid to be measured flows, a pressure receiving plate disposed downstream of the vortex generator in the measurement tube, and embedded in the pressure receiving plate And a vortex detector for detecting a change based on the Karman vortex by detecting a fluctuating pressure based on the Karman vortex generated by the vortex generator by the pressure detecting element plate via the pressure receiving plate. Equipped with vortex detection means Both the thermal type detection means for arranging vertically heating temperature sensor constituting the flow direction of the flow path by rodlike flow rate sensor having a function of temperature-sensitive sensor and the temperature sensor and the heating sensors constituting the temperature sensor of the rod-shaped A multi-vortex flowmeter comprising a converter case, and a flow rate converter provided with an amplifier board having a microcomputer configuration inside the converter case, on the upstream side of the measuring tube and A pressure measurement unit is formed in the vicinity of the measurement tube, and the pressure measurement unit is provided with a portion for accommodating the pressure gauge and a pressure receiving port for guiding a part of the fluid to be measured flowing through the flow path, the vortex detector, against the flow transducer at a position spaced upstream of the temperature-sensitive sensor and the heating temperature-sensitive sensor, the vortex detector and the measured flow through the flow path are wired together with the thermal type detection means It is characterized in providing integrated pressure gauge for measuring the pressure of the.

According to the present invention having such a feature, the measurement value of the pressure gauge is taken into the flow rate converter, so that it is possible to grasp the case where the vortex differential pressure is high even when the flow rate is low. It becomes possible to lower the lower limit flow rate, which is a judgment criterion at the time. The pressure gauge integrated with the flow rate converter has the advantage that it is not necessary to consider the influence of disturbance on the wiring, etc., compared to the case of separately installing the pressure gauge with respect to the multi-vortex flow meter. As a result, the detection accuracy and the like can be increased. In addition, the pressure gauge integrated with the flow rate converter has the advantage that setup is easier compared to the multi-vortex flow meter, and the pressure measurement at the optimum position is possible. It has the advantage of being possible.
Furthermore, according to the present invention, since the pressure measurement unit is formed and the pressure gauge is housed therein, pressure measurement can be performed without affecting the detection of the change based on the Karman vortex.

  According to the present invention, there is an effect that it is possible to provide a multi-vortex flowmeter that is much better than before. Moreover, according to this invention, there exists an effect that a flow volume can be measured using the function of a vortex flowmeter as much as possible.

  Hereinafter, description will be given with reference to the drawings. FIG. 1 is a front view showing an embodiment of a pressure gauge integrated multi-vortex flow meter according to the present invention. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view of the flow rate converter.

  1 and 2, reference numeral 1 denotes a multi-vortex flow meter (multi-vortex flow meter integrated with a pressure gauge) of the present invention. The multi-vortex flow meter 1 is configured to have both the function of a vortex flow meter and the function of a thermal flow meter. In addition, as will be described later, the multi-vortex flow meter 1 is configured to have a structure capable of lowering a lower limit flow rate that is a criterion for switching. The multi-vortex flow meter 1 includes a vortex detection means 7 having a measurement mounting pipe 2, a pressure gauge 3, a measurement pipe 4, a vortex generator 5, and a vortex detector 6, a temperature sensor 8 and a heating temperature sensor 9. And a flow rate converter 11 for calculating a flow rate or a flow rate of a fluid to be measured (not shown) based on output signals from the vortex type detection unit 7 and the thermal type detection unit 10. Has been. Hereinafter, each configuration will be described with reference to FIGS. 1 to 3.

  The measurement attachment pipe 2 is detachably attached to the middle of the flow pipe 12 (not limited to the middle of the flow pipe 12 but may be attached to the end), and the flow path 13 is formed in the inside thereof. It is formed as such a cylindrical structure. Joints are formed at both ends of the measurement mounting pipe 2. The flow rate converter 11 is fixed to the outside of the measurement mounting pipe 2 by appropriate means. The flow path 13 formed in the measurement mounting pipe 2 has a circular cross section. A fluid to be measured flows in the flow path 13 in the direction of the arrow.

  A measuring tube 4, a temperature sensor 8, and a heating temperature sensor 9 are provided in the middle of the flow path 13. In addition, a pressure measurement unit 14 is formed on the upstream side of the measurement tube 4 and the like and in the vicinity of the measurement tube 4 (the arrangement is an example). The pressure measuring unit 14 is attached in such a state that the pressure gauge 3 is accommodated. The pressure measurement unit 14 has a part for housing the pressure gauge 3 and a part for introducing a part of the fluid to be measured flowing through the flow path 13. The pressure gauge 3 is for measuring the pressure of the fluid to be measured flowing through the flow path 13, and here, a known pressure gauge is used (however, the pressure gauge 3 can be used for the flow rate converter 11). . The pressure gauge 3 is attached to the flow rate converter 11 so as to be integrated. The pressure gauge 3 is integrated with the flow rate converter 11 at a position slightly upstream from the vortex detector 6, the temperature sensor 8, and the heating temperature sensor 9.

  The measuring tube 4 is formed in a cylindrical shape having a rectangular tube cross section (the shape is an example). The measuring tube 4 is formed so as to extend along the arrow direction in which the fluid to be measured flows. A vortex generator 5 and a pressure receiving plate 15 (described later) located on the downstream side of the vortex generator 5 are provided at a portion of the measurement tube 4 where the fluid to be measured flows. Outside the measuring tube 4, a temperature sensor holding unit 16 is provided to hold the tips of the temperature sensor 8 and the heating temperature sensor 9 (in this embodiment, it is integrated, but not limited to this). The measurement tube 4 is fixed to the vortex detector 6 via the connecting cylinder portion 17. In this embodiment, the vortex detector 6 connected to the measurement tube 4 is attached to the measurement attachment pipe 2 so as to be detachable.

  The vortex generator 5 is a part for generating a vortex inside the measurement tube 4 and is configured to face the flow of the fluid to be measured. In this embodiment, the vortex generator 5 is formed in a triangular prism shape (the shape is an example. Japanese Patent No. 2869054 of Patent Document 1 discloses several examples). The vortex generator 5 is provided in the opening portion of the measuring tube 4 on the side into which the fluid to be measured flows. The vortex generator 5 is provided so as to be located at the center of the opening of the measurement tube 4.

  Here, the vortex generated by the vortex generator 5 will be described. The vortex is separated from the position where the change in momentum generated by the flow of the fluid to be measured flowing into the opening portion of the measuring tube 4 along the vortex generator 5 is large, and the cross section of the vortex generator 5 is like this embodiment. In the case of a triangular shape, the triangular edge portion becomes the peeling point. The vortices that peel off and flow out of the vortex generator 5 are alternately generated in a staggered manner according to Karman's stable vortex condition, and flow out while forming a vortex array that maintains a constant vortex distance and vortex string distance. The distance between the vortices is the unit time calculated based on the number of vortices generated per unit time, that is, the vortex frequency and the flow rate obtained from the fluid flowing into the reference container such as the reference tank within a predetermined time. It can be obtained from the hit flow rate.

  The temperature sensor holding part 16 is formed so as to protrude from the lower wall of the measurement tube 4 in the horizontal direction, in other words, from both side walls of the measurement tube 4. The temperature sensor holding part 16 is not particularly limited, but is formed so that the shape in plan view is a triangle. The temperature sensor holding part 16 is formed in a shape in which the measuring tube 4 has a fin. The tips of the temperature sensor 8 and the heating temperature sensor 9 are inserted straight into the vicinity of the triangular top of the temperature sensor holding unit 16.

  The vortex detector 6 is a sensor for detecting vortices, and a pressure receiving sensor is used here. The vortex detector 6 includes a pressure receiving plate (sensor pressure receiving plate) 15 disposed on the downstream side of the vortex generator 5 in the measurement tube 4 and a pressure detection element plate provided inside the vortex detector 6. The fluctuating pressure (alternating pressure) based on the Karman vortex generated by the vortex generator 5 is detected by the pressure detecting element plate via the pressure receiving plate 15. In this embodiment, the vortex detector 6 is attached so as to be integrated with the flow rate converter 11.

  The vortex detection means 7 is provided for obtaining the flow velocity or flow rate of the fluid to be measured flowing in the measurement mounting pipe 2. The flow rate or flow rate of the fluid to be measured flowing in the measurement mounting pipe 2 is obtained by calculating the flow rate or flow rate of the fluid to be measured flowing in the measurement pipe 4 as the partial flow rate or partial flow rate of the measurement mounting pipe 2. It is supposed to be. This is based on the fact that the entire flow rate can be estimated if the flow is uniform even if a part of the pipe section of the measurement mounting pipe 2 is measured instead of the whole pipe cross section. That is, since the flow velocity distribution of the rectified fluid flowing through the straight pipe is given as a function of the Reynolds number, the flow velocity at a certain distance from the center of the measurement attachment pipe 2 is averaged in the measurement attachment pipe 2. It can be converted into a flow rate.

  As the temperature sensor 8 and the heating temperature sensor 9 constituting the thermal detection means 10, known ones are used. Here, the description of the specific configuration is omitted. The temperature sensor 8 of this embodiment is a rod-shaped temperature sensor, and the rod-shaped heating temperature sensor 9 is also a flow rate sensor (heater) having functions of a temperature sensor and a heating sensor. In this embodiment, the temperature sensor 8 and the heating temperature sensor 9 are attached to the flow rate converter 11 so as to be integrated.

  The temperature sensor 8 and the heating temperature sensor 9 protrude into the flow path 13 of the measurement mounting pipe 2, and the most advanced part is held by the temperature sensor holding part 16. Each temperature sensing part of the temperature sensor 8 and the heating temperature sensor 9 is arranged in the vicinity of the measuring tube 4. The temperature sensor 8 and the heating temperature sensor 9 are arranged side by side with the vortex detector 6 (the arrangement is an example. If the arrangement is made so as not to affect the vortex detection, the temperature sensor 8 and the heating temperature sensor 9 may be different. But shall be fine). It should be noted that each temperature sensing part of the temperature sensor 8 and the heating temperature sensor 9 may be elongated so as to protrude further from the temperature sensor holding part 16 to the center of the flow path 13 (measured from the outside). To avoid the effect of heat transmitted to the mounting pipe 2).

  The flow rate converter 11 has a converter case 18. Inside the converter case 18, an amplifier board 19 having a configuration such as a microcomputer is provided. The amplifier board 19 is connected to the transmission line 20 of the pressure gauge 3, the leads of the temperature sensor 8 and the heating temperature sensor 9, and the transmission line 21 of the vortex detector 6 (sensation in FIG. 3). The arrangement of the temperature sensor 8 and the heating temperature sensor 9 is changed for convenience, and is actually arranged at a position rotated by 90 °, and aligned with the transmission line 21 of the vortex detector 6 in the direction perpendicular to the paper surface of FIG. Arranged).

  The temperature sensor 8, the heating temperature sensor 9, and the transmission lines 20 and 21 are drawn into the converter case 18. The temperature sensor 8, the heating temperature sensor 9, and the transmission lines 20 and 21 are drawn into the converter case 18 without being exposed to the outside. The temperature sensor 8, the heating temperature sensor 9, the pressure gauge 3, the vortex detector 6, and the amplifier board 19 have functions as a flow rate measurement unit and a flow rate calculation unit.

  A converter cover 24 having a switch board 22 and a display board 23 is attached to the opening of the converter case 18 with a packing (not shown) interposed therebetween. A transmission cable 25 is connected to one side wall of the converter case 18.

  In the above configuration and structure, the multi-vortex flow meter 1 of the present invention has a function of a vortex flow meter and a function of a thermal flow meter according to the flow state of the fluid to be measured flowing through the flow path 13 of the measurement mounting pipe 2. Can be used properly. That is, measurement is performed by the function of the thermal flow meter in the minute flow rate region and the low flow rate region, and measurement is performed by the function of the vortex flow meter in the high flow rate region. The multi-vortex flow meter 1 of the present invention is designed to wrap to some extent the high flow rate measurement in the function of the thermal flow meter and the low flow rate measurement in the function of the vortex flow meter, and is switched by the flow rate converter 11. Is to be done.

  First, an operation when measuring a minute flow rate region or a low flow rate region, that is, an operation when measuring by the function of a thermal flow meter will be described. The heating temperature sensor 9 measures the flow rate based on the temperature detected by the temperature sensor 8. That is, in the flow rate measurement unit and the flow rate calculation unit in the flow rate converter 11, the heating temperature sensor 9 is heated so that the temperature difference between the temperature sensor 8 and the heating temperature sensor 9 is constant (for example, + 30 ° C.). (Make the current flow) and calculate the mass flow rate from the current value related to this heating. The calculated mass flow rate is converted into a predetermined unit, and then displayed on a display unit provided on the upper portion of the converter cover 24 or transmitted by the transmission cable 25 and displayed on a display device (not shown).

  If it explains supplementarily about calculation of the above-mentioned mass flow rate, when fluid under measurement (illustration omitted) is poured in the direction of an arrow, heating temperature sensor 9 will be cooled with fluid under measurement. In order to control the temperature difference with the temperature sensor 8 to be constant, it is necessary to further pass a current through the heating temperature sensor 9. At this time, it is known that the current flowing through the heating temperature sensor 9 is proportional to the mass flow rate, and the mass flow rate is calculated using this.

  Next, the operation in the case of performing measurement by the function of the vortex flow meter will be described. Fluctuating pressure (alternating pressure) based on Karman vortices generated by the vortex generator 5 is detected by the pressure receiving plate 15 and the pressure detecting element plate. Then, the flow velocity or flow rate of the fluid to be measured flowing in the measurement tube 4 is calculated as the partial flow velocity or flow rate of the measurement attachment pipe 2 from the detection value in the vortex detector 6, and the measurement object flowing in the measurement attachment pipe 2 is obtained. Calculate the flow rate or flow rate (volume flow rate) of the fluid. The calculated flow velocity or flow rate is converted into a predetermined unit, and then displayed on a display unit provided on the upper portion of the converter cover 24 or transmitted by the transmission cable 25 and displayed on a display device (not shown).

  Regarding the switching related to the function of the flow meter performed in the flow rate converter 11, the measured value from the pressure gauge 3 is taken into the flow rate converter 11, and taking into account the taken measured value, Switching from the function to the function of the vortex flowmeter or from the function of the vortex flowmeter to the function of the thermal flowmeter is performed. For example, even if the flow rate is low, the vortex differential pressure increases as the pressure in the measurement mounting pipe 2 rises. Therefore, when switching from a thermal flow meter or when switching to a thermal flow meter, this The lower limit flow rate serving as a determination criterion is lowered, and switching is performed based on the lower limit flow rate after the lowering.

  As described above with reference to FIGS. 1 to 3, according to the present invention, it is possible to provide a multi-vortex flow meter 1 that is much better than the conventional one. The multi-vortex flowmeter 1 can measure the flow rate of the fluid to be measured with high accuracy from zero or a minute flow rate to a large flow rate.

  Regarding the effects of the multi-vortex flowmeter 1 of the present invention, a few more will be listed. The pressure gauge 3 is integrated with the flow rate converter 11, and the pressure gauge 3 is integrated with the temperature sensor 8, the heating temperature sensor 9, and the vortex detection. Since the wiring is connected to the flow rate converter 11 together with the vessel 6, the piping and wiring structure can be simplified as compared with the case where the pressure gauge is provided separately from the multi-vortex flow meter 1. Moreover, since the transmission line 20 of the pressure gauge 3 is not exposed to the outside as can be seen from the state shown in the drawing, it is possible to make a flowmeter that is strong against disturbance and hardly causes erroneous detection. Furthermore, by integrating the pressure gauge 3 into the flow rate converter 11, it is easier to set up and measure the pressure in the vicinity of the measuring tube 4, in other words, optimal compared to the case where the pressure gauge is separately provided. The pressure can be measured at various positions.

  In addition, in the case of a separate installation of the pressure gauge, there is a risk that processing that affects the dynamic pressure may be performed in the operation of the separate installation. However, in the present invention, since the pressure gauge 3 is integrated with the measurement mounting pipe 2 in advance, no processing that affects the dynamic pressure is performed.

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

It is a front view which shows one Embodiment of the pressure gauge integrated multi vortex flowmeter of this invention. It is the sectional view on the AA line of FIG. It is sectional drawing of a flow rate converter.

Explanation of symbols

1 Multi-vortex flow meter (Integrated multi-vortex flow meter with pressure gauge)
2 Measurement mounting pipe 3 Pressure gauge 4 Measurement pipe 5 Vortex generator 6 Vortex detector 7 Vortex detector 7 Temperature sensor 9 Heating temperature sensor 10 Thermal detector 11 Flow rate converter 12 Flow pipe 13 Flow path 14 Pressure Measuring unit 15 Pressure receiving plate 16 Temperature sensor holding unit 17 Connecting cylinder unit 18 Converter case 19 Amplifier board 20, 21 Transmission line 22 Switch board 23 Display board 24 Converter cover 25 Transmission cable

Claims (1)

A measuring tube that is provided in the flow path, is formed in a cylindrical shape having a square tube cross section, is formed so as to extend along a direction in which the fluid to be measured flows, and passes the fluid to be measured;
A vortex generator that is provided to be positioned at the center of the opening of the measurement tube through which the fluid to be measured flows, so as to face the flow of the fluid to be measured. When,
Fluctuating pressure based on Karman vortices generated by the vortex generator comprising a pressure receiving plate disposed on the downstream side of the vortex generator in the measurement tube and a pressure detection element plate embedded in the pressure receiving plate via the pressure receiving plate. A vortex detector for detecting changes based on Karman vortices detected by a pressure sensing element plate ;
A vortex detection means having
A temperature detection sensor configured by a rod-shaped temperature sensor, and a thermal detection means for arranging a heating temperature sensor configured by a rod-shaped flow velocity sensor having the functions of a temperature sensor and a heating sensor , perpendicular to the flow direction of the flow path ,
Further, in a multi-vortex flowmeter comprising a flow rate converter having a converter case and provided with an amplifier board having a microcomputer configuration inside the converter case ,
A pressure measuring unit is formed on the upstream side of the measuring tube and in the vicinity of the measuring tube, and the pressure measuring unit includes a portion for storing the pressure gauge and a pressure receiving port for guiding a part of the fluid to be measured flowing through the flow path. the provided, the vortex detector, the feeling against the flow transducer at a position spaced upstream of the temperature sensor and the heating temperature sensor, the flow to be routed together with the vortex detector and the thermal type detection means A pressure gauge integrated multi-vortex flowmeter, wherein a pressure gauge for measuring the pressure of the fluid to be measured flowing through the passage is integrally provided.

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